Plugged steam boiler sections

bob young

ever try using arsenic ?

mark_28

Plugged steam boiler sections

I am servicing an aging steam system consisting of two (almost) fully redundant 1700 mbh American Standard boilers. The one that has borne most of the load over the past 30 years is alternately flooding and going off on LWCO. To make a very long story short, here's the problem: The boiler is 13 sections: the center section has the only (6") steam takeoff and condensate enters on the left end. The right hand end section is the connection point for a MM # 51 cutoff and feed valve and the gauge glass is on the left end. When the glass shows plentiful water, the body of the 51 is dry. Naturally, I thought the piping was plugged but we opened all this up and it's clean. Draining and refilling the boiler demonstrated that at least the right end section and maybe more get only the water that seeps through from the other sections. Worse yet, the sections appear to be connected diagonally top and bottom as you would expect but the end sections are tapped in the center only, precluding any straight ramrod through the base. It would appear that the "dead end" right section is filled with hard sludge or calcium and is now isolated from the rest of the boiler. Is there any way I can clean this up chemically? Am I missing something in the diagnosis? Any help on this mess would be greatly appreciated.

ttekushan_2

I've encountered this

more times than you can imagine. As a matter of fact, just worked on an American Standard that was plugged. Opened the sill cock and nothing came out. (always have valve washers on hand) Anyway, it took several VERY long treatments with a proper hydrochloric acid for this purpose. The HCl acids for boilers are inhibited so they won't attack the metal for awhile (you usually have about 8 hrs to work with). This took so long because it was clear that the bottom of at least one section was so thoroughly plugged that the exposed calcium surface was quite small, until the acid could work deep into the blockage.
I prefer to use an acid that changes color as the process occurs, and includes litmus paper to confirm neutralization upon completion.
This can be a tricky process as incomplete treatments (like those you have to stop after 8 hours because someone would actually like to have heat) will often cause surging. I always carry some of the old fashioned additive that contains diatomatious earth to capture impurities and drop them out of suspension. This stuff cures the surge almost immediately and dries the steam. This only works if you COMPLETELY flush out the acid first.

I talked recently with a man who used to work for a major CI boiler manufacturer. They would collect sample failed boilers for inspection. Invariably the ones with overheated and cracked sections were those that were plugged. He said they would take a plasma cutter to them and find sections filled with what was for all intents and purposes, CONCRETE.

Leaving a plugged boiler alone is a recipe for extraordinarily inefficient operation and premature catastrophic failure.

-Terry

ttekushan_2

I've never been

so troubled by steam trouble to consider ending it all. It seems a bit extreme for such minor troubles! Or was I thinking hemlock? Hehe.

michael terry

you guys ever see

like a black gray mud in boiler sections, my customer thinks its coming from leaks in underground piping, i think its from all the make water they are using and its eating the boilers. so far three years and three cracked sections. I just recently got involved with the problem.
is this mud coming from the consumption if the sections?
they are making up large amounts of water everyday.

soot_seeker_2

Of course.

Stop adding the makeup water. That's the problem.

And that probably means fixing the leaks too.

Ed

mark_28

Thanks for your comments. Boiler #2 is big enough and working well enough that I think I can take enough time to eat away at this stuff and maybe get it out of there. After all, what choice do we really have? If we run the boiler as is, it'll split wide open. Not much to lose here.

Mark